Frost dragons are vulnerable to stab attacks. Each individual dragon will only use one of magic or ranged, not both, in addition to melee and dragonfire. It is highly recommended to use the protect prayer corresponding with their distance attack, as their melee attacks are less accurate. You should use either a super antifire potion, or an anti-dragon shield or dragonfire shield along with a regular antifire potion to fully shield yourself from their dragonfire attacks.

Occasionally a blue light will appear around the dragon. Any attack directed at the dragon while the light is active will cause heavy damage to you (this does not apply to damage done by the dwarf cannon, but the cannon cannot hit a dragon with blue light around it). The only solution is to wait it out. Dreadnip's can still cause damage that is not reflected back during this phase.
It is not possible to use High alchemy on your drops or any other items while inside the dungeon.